STAT2 gene rescued IFNα response in P117 MEFs. (A) P117 MEFs were infected with MigR1, MigR1-hSTAT2 or MigR1-mSTAT2 recombinant retrovirus. The infection efficiency was indicated by the percentage of GFP positive cells. P117 MEFs restored with vector alone (v), human STAT2 (hST2) or mouse STAT2 (mST2) gene were left untreated (medium, empty bars) or treated with 250 U/ml IFNα for 3 h (solid bars) followed by RT-QPCR using primers to OAS (B) or PKR (C). Relative mRNA was shown by normalizing the values of OAS or PKR to that of β-actin.